We propose to develop and optimize a micro particle vaccine that can prevent, treat and possibly reverse tissue- and organ-specific autoimmune disease, like type 1 diabetes mellitus. The vaccine consists of a microsphere formulation of a mixture of antisense oligonucleotides (ODN) that knock-down the expression of the CD40, CD80, and CD86 co- stimulatory gene primary transcripts and are targeted specifically to dendritic cells. Co-stimulation knock-down in dendritic cells re-orients their homeostatic state into a population of cells that orchestrate the suppression of autoimmunity. The activities under this proposal will include the manufacture of a panel of these DC-targeted formulations and identification of those that are taken up specifically by dendritic cells but no other cells that constitute the skin, the proposed site of administration. These candidate microspheres will then be subjected to a series of tests to identify no more than two that meet a clinically-oriented Target Product Profile (TPP). The first two aims will be directed towards the manufacture, characterization, optimization and selection of formulations that meet the TPP and the last aim will seek to demonstrate, first in a disease-agnostic manner, and then, in a type 1 diabetes - specific application, mechanism-based metrics of immune activity. The intellectual merit of the proposed activity is to better understand how ODN microspheres convert dendritic cells into orchestrator cells that direct other tiers of immune cells to suppress an active autoimmunity to specific organs and tissues. Targeting type 1 diabetes with these formulations will offer insights into how reprogrammed dendritic cells achieve their beneficial effects inside lymph nodes, under disease-agnostic models, and the pancreatic lymph nodes in type 1 diabetes and how the regulatory cells responding to this orchestration are stimulated to do so. These are questions that remain unaddressed in the field of autoimmunity. The broader impacts of the proposed activities are primarily on the treatment approach for organ- and tissue-specific autoimmune disease. The technology would impact how one treats and potentially reverses Crohn's disease, rheumatoid arthritis, autoimmune lymphocytic thyroiditis, and multiple sclerosis. Compared to the current and expected therapeutic options with significant toxicities along with substantial manufacturing expense, an off-the-shelf vaccine that reprograms DC to orchestrate immunosuppression specifically for the organ/tissue drained by the same lymphatics as the vaccine injection site, represents a low-cost, mechanistically-driven option that can be scaled up quickly to treat large populations. The direct and short-term potential commercial impacts are primarily on how type 1 diabetes is treated. The proposed innovation could compete with, or be added to insulin therapy, as a once-a-month and potentially once-a-year prophylactic in high risk individuals not yet diabetic, or as a reversal agent in new onset disease. Even though type 2 diabetes is not autoimmune, there is solid evidence that some type 2 patients exhibit latent autoimmunity. Our product could control this autoimmunity while insulin is obviated. This technology can be potentially extended to also facilitate allograft survival when the site of transplantation is sub served by lymphatics that drain into lymph nodes sub serving the formulation administration site.